Silt fence apparatus and method of construction

ABSTRACT

The invention is a silt screen fence assembly which combines the use of a polymeric silt screen fabric with or without a plastic reinforcement member and a thermoplastic support stake with a hot melt adhesive to attach the silt screen fabric with or without the reinforcement member to the support stake to provide an extremely durable and tenacious bond of the screen fabric to the support stake so as to overcome the inherent problems with prior art silt screen fences wherein the mechanical bond is initially significantly weakened due to penetrating, cutting, punching, or thinning out the silt screen or reinforcement material upon assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/724,876, filed on Mar. 16, 2007 which claims the benefit ofU.S. Provisional Patent Application Ser. No. 60/783,562, filed on Mar.17, 2006.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A SEQUENCE LISTING

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a system for minimizingerosion of a site of soil, more particularly, the invention pertains tothe provision of a material and system for minimizing the erosion ofsoil during a construction period.

2. Description of the Related Prior Art

In excavating and grading work, such as in the construction of golfcourses, highways, shopping centers, or other commercial and residentialconstruction, the work often results in large areas of mounds of soilwhich may lay undisturbed for several months until the project iscompleted and graded. Often, these areas are subjected to severe weatherconditions such as rain or storms resulting in severe run-off as aresult of the surface water carrying the soil to various unwanted areas.The run-off water contains fine soil, small stones, and a large amountof silt. The run-off will often block drains, as in a subdivision,contaminate streams as in the construction of golf courses as well asponds, and kill vegetation, depending on the flow of the run-off and thelength of time such action occurs.

The natural way to prevent this type of run-off is to seed the area toprovide growth of vegetation which will then hold the soil in place.However, the time it takes to seed the area and grow appropriatevegetation to contain or prevent the run-off is often long term andunder the present environmental regulations, run-off during the periodof time that it takes to grow the vegetation is generally notacceptable. Temporary seeding is also an unneeded expense.

To solve this well known problem, the prior art has proposed the use ofstraw bales selectively placed to avoid the acceleration of the waterrun-off thereby preventing the erosion of the soil. The bales aremaintained in place by driving a stake into the ground through the strawbale. This form of solution is strictly temporary since water will findnew paths and the problem will often reappear shortly after the bales ofstraw have resided in one place for a period of time. Other solutionsare known to exist in the prior art. For example, Olsen, U.S. Pat. No.2,872,161, discloses the use of a fencing structure wherein a flexiblesheet formed fencing material supported in a generally vertical spreadcondition, by means of plural element post units which may be suitablyspaced apart throughout the length of any particular fence. The objectof the improved fencing structure is to provide a relatively inexpensivefencing structure wherein flexible sheet material of suitable width maybe utilized as a barrier medium; the flexible sheet material beingengaged between and around the posts of suitably spaced plurality ofposts supporting units between which the sheet material extends in atensioned condition and by which the sheet material is maintained ingenerally fully spread conditions.

Another method which has been used in the prior art is disclosed inGagliardy et al., U.S. Pat. No. 4,279,535, which proposes a fabricmaterial that has special characteristics of strength and porosity tominimize the flow of silt suspended in ground water while having therequisite strength to resist abrasion and tearing occasioned by thefield conditions. Such fabric consists of a lamination of one or morewebs of a relatively fragile non-woven fabric of relatively uniformporosity and formed from filaments of relative cross-section to a webformed from filaments arranged in a grid pattern, the later filamentsbeing of relatively larger cross-section relative to the cross-sectionof filaments to the non-woven material. In installation, one edge of thefabric is buried in a trench in the ground and the other edge issupported above the ground in a fence like configuration on a series ofposts or stakes which are driven or otherwise secured in the ground. Tofacilitate the attachment of the upper edge of material to the post, oneedge of the strip of the laminated material is folded over to form a hemwhich is securely stitched to provide a longitudinally extending pocketwherein a cord, cable, or the like, is disposed to provide means forreadily supporting the upper edge of the fabric in a taut condition.Grommets are utilized to tie the fabric fence to the individual posts.

Wright, III, U.S. Pat. No. 4,756,511, discloses a web wherein the web ofthe fencing material is mounted to stakes in a simple and economicalmanner. Wright teaches the use of a mounting strip which is securedagainst the stake with the fabric therebetween. The mounting strip makescontact with the fabric over an extended width of the fabric so thatthere is a surface securement instead of the simple space pointsecurement as in the prior art. The mounting strips and fabric may besecured to the stakes in any suitable manner such as by conventionalfasteners, including staples, nails, and the like. Wright further pointsout that conventional means of securement is unsatisfactory wherebyfasteners and staples are used because the staples tend to tear throughthe fabric web when exposed to environmental conditions such as highwinds, snow drifts, and the like. Accordingly, the use of a contactstrip avoids these difficulties.

Because the construction of silt fences is susceptible to adverseeffects produced by the wind, Shea, U.S. Pat. No. 5,758,868, disclosesand teaches a means for securing a flexible plastic fencing material toa fence post element which provides a silt fence which is more windresistance and maintenance free. The fence consists, in combination, ofa plurality of post units, a flexible plastic fencing material havingrigid rod means at two opposing ends wherein each of the post unitsconsist of about three continuous hollow elongated tubes, the centraltube contains a retractable stabilizing means for ground insertion; andwherein the outer tubes have a slit along their longitudinal length toaccommodate the rod means of the fencing material. The three continuoushollow elongated tubes provide appropriate fastener elements and securethe flexible fencing material in position to eliminate damage to thefence material caused by wind effects.

Finally, Root, U.S. Pat. No. 6,824,332 discloses a production method fora silt fence flat pack wherein silt fabric is attached to a number ofevenly spaced stakes, the stakes then being bunched together so that thesilt fabric hangs between the stakes in descending loops. The bunchingis continued until all of the stakes lie close together in one plane.The loops of silt fabric are then wrapped tightly around the stakes.Securing bands are then placed around the assembly to create a flatpack.

What is needed however is a method of securing a silt fence fabricmaterial to a support stake that does not penetrate, cut, break, or thinthe silt screen or reinforcing surfaces to avoid tearing of the fabricweb when exposed to environmental conditions, such as high winds, snowdrifts, and the like. Further, where fasteners are used, the puncturingof the material by the fastener tends to provide a weak point wheretears and holes are started and continue as a result of environmentalconditions.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to an improvement in the manner ofsecuring the flexible plastic silt fencing material to a fence post orstake which provides a silt fence which is desirable, maintenance free,less subject to damage due to wind conditions, and much more economicalto build and maintain. The invention completely avoids the shortcomingof the mechanical methods of attachment (i.e. staples, hog rings,nailing, or sandwiching between posts, etc.) where strength reduction iscaused by the penetrating, cutting, tearing, breaking or thinning of thesilt screen material or reinforcement surfaces due to the attachmentprocedure used.

Many of the prior art shortcomings due to mechanical attachment areremedied by the use of a non-mechanical method of assembly by directlybonding the screen and/or reinforcement surfaces to the post or supportsurfaces with an adhesive thereby creating an infinite number offastening points. The invention does not penetrate, cut, break, or thinthe silt screen or reinforcement member surfaces, and thus, does notmechanically reduce the initial strength of the bond or materialstrength of the silt screen fabric or reinforcing member surfaces.

The invention proposes the use of thermoplastic stakes with athermoplastic silt screen fabric. The silt screen fence is manufacturedin rolls which are formed by a plurality of thermoplastic stakesattached to the silt fabric at preselected intervals. After the firststake is adhesively attached to the thermoplastic silt screen fabric,the stake is rotated to wind the silt fabric around itself on the stake.At preselected intervals, another stake is adhesively attached to thesilt fabric and the winding continues until a complete roll ofpreselected size is formed. The roll can be made of any size, generally100 foot rolls are typical.

If a reinforcement member is required, the same technique is used,except both the reinforcement member and the silt fabric are adhesivelyattached to the first stake and wound together until subsequent stakesare adhesively attached at selective intervals during the windingprocess.

The bonding of the stakes to the silt screen with or without thereinforcement member is accomplished by the use of a hot melt adhesive,when using an adhesive that has a surface tension lower than the surfacetension of the outer surface of the stake members. The bonding is almostinstantaneous and requires just a few seconds of time to cure so thatthe technique of manufacturing by rolling the silt screen, with orwithout the reinforcement member upon an attached stake and winding thesilt screen material upon itself with additional stakes bonded atpreselected intervals, can be a continuous process because the hot meltadhesive requires a very short curing period. The curing of themolecular bond is almost instantaneous.

If required for the application, an alternate arrangement can be made.For example, the stake can be manufactured from a highly-glass-filledpolypropylene with the use of a polyolefin silt screen with or withoutreinforcement, attached to the stake by the use of hot melt adhesive.The same method can be used for manufacturing rolls of this extremelydurable material.

Accordingly, it is an object of the invention to provide a relativelyinexpensive silt fence capable of being readily installed by relativelyunskilled labor, and utilizing silt fencing material of flexible sheetmaterial which may be conveniently supplied in rolls of desired widthand length. The sheet material, with or without a reinforcing member, issupported and maintained by adhesively bonded plastic posts.

It is a further primary object of the invention to provide a siltfencing system which can be readily installed so that its effectivenessin impeding the flow of ground water to minimize the run-off of the siltand soil is readily utilized.

It is a further object of the invention to provide a silt fence whichincludes means for securely mounting the web to the stakes without thereduction of the strength of the web by penetrating, cutting, breaking,or thinning the silt screen web or reinforcing material.

It is yet a further object of the invention to provide a silt fencewherein the web may be mounted to the stakes in a simple and economicalmanner.

It is yet a further object of the invention to provide a silt fencewhich is readily recyclable.

These objects and other features, aspects, and advantages of thisinvention will be more apparent after a reading of the followingdetailed description, appended claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of the silt fence assembly components usingonly the woven silt fabric without a reinforcement member;

FIG. 2 is a perspective view of the silt fence assembly componentsincluding the use of a reinforcement member;

FIG. 3 is a perspective view of the silt fence assembly using only thewoven silt fabric without a reinforcement member; and

FIG. 4 is a perspective view of the silt fence assembly including theuse of a reinforcement member.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-4 illustrate a silt fence assembly 10 in accordance with theinvention. The silt fence assembly 10 includes a plurality of supportstakes 12, preferably made from plastic, each of which consists of alongitudinal body portion 14 terminating in a pointed end 16 so that thepointed end 16 may be penetrated into the ground surface for anchoringthe plurality of support stakes 12 in an upright position. Although thepreferred embodiment is a plastic material for the support stake 12, itis understood that the support stake 12 may be fabricated of anyplastic, metal, wood, or wood composite material or size of anyconvenient cross-section as dictated by the specific application.

As also illustrated in FIGS. 1-4, the silt fence assembly 10 includes aweb or silt fabric screen 18 of any suitable woven polymeric fabric.Woven silt fabrics using synthetic yarns have been used increasingly inrecent years to prevent soil run-off at construction sites. Thesefabrics are generally designed to have predetermined water flow capacityper square foot of area, while also having the capability of retainingsoil particles of predetermined size. Some woven fabrics have been knownto use yarn with substantial flat and rectangular cross-sections,sometimes called tape or ribbon yarn which are woven together using aplain weave while others employ very wide, flat tape yarns in the warpand weft which are woven together with a twill-type weave in a highlycompacted fashion in each of the warp and weft. Still others are wovenfrom tape yarns and either bulked continuous filament yarns or spunyarns for specialty applications. The specific construction is selectedas dictated by the need to achieve appropriate water flow rates throughthe fabric while at the same time retaining relatively smaller soilparticles. FIGS. 1-4 illustrate the mounting means used for securing thepolymeric fabric to the support stakes 12 without the deleterious effectof penetrating the silt fabric screen 18. A bead of hot melt adhesive 20is laid along the longitudinal body portion 14 of the support stake 12.The silt fabric screen or web 18 is then pressed against the bead of hotmelt adhesive 20 with or without an applicator tool. An applicator toolis preferred so as to provide a cooling effect to the hot melt adhesive20 and the instant cooling solidifies the hot melt adhesive 20 in a fewseconds to create a permanent bond. If a reinforcement member 22 isrequired, as shown in FIGS. 2 and 4, the silt fabric screen 18 is placedin contact with the reinforcement member 22 before both layers arepressed against the bead of hot melt adhesive 20 on the support stake12. Again, an applicator tool may be used to press both layers of thesilt fabric screen 18 and reinforcement member 22 against the supportstake 12 and after a few seconds; the hot melt adhesive 20 solidifies tobond both the reinforcement member 22 and the silt fabric screen 18 tothe support stake 12.

The reinforcement member 22 is made of any convenient woven materialwith a woven texture creating substantially larger interstitialdistances than the woven silt fabric screen 18 so as to function as asupport to the silt fabric screen 18 with no other function.

The use of an adhesive bond avoids the deleterious effect of reducingthe initial strength of the woven fabric layer by penetrating, cutting,breaking, or thinning the fabric material when using a mechanicalfastener or stretching the fabric between adjoining stakes. In thepreferred embodiment, the bonding of the silt fabric screen 18 with orwithout the reinforcement member 22 is accomplished by the use of a hotmelt adhesive No. 4199 available from Hot Melt Technologies, Inc.,Rochester Hills, Mich. However, it is not intended to limit the adhesiveto this specific composition. The invention proposes to use any rapidcuring adhesive that is wettable with the substrates to be bound and hasa surface tension equal to or lower than the substrates to be bound.With this arrangement, low surface energy materials such as the supportstakes will become molecularly bound with the woven polymeric fabricscreen and requires a permanent bond with the silt fabric screen as wellas the reinforcement member, when used. In general, adhesives that canwet a surface of a substrate that have a surface tension below 40dynes/cm maybe used, although the ability to wet a substrate that has asurface tension below 35 dynes/cm is preferred. Such adhesives arecommercially available from adhesive manufacturers. The preferredembodiment further proposes the use of a thermoplastic support stake 12with a thermoplastic silt fabric screen 18 with or without athermoplastic reinforcement member 22 attached to the thermoplasticsupport stake 12 with a thermoplastic hot melt adhesive 20.

Such combination yields an extremely durable and tenacious bond of thesilt fabric screen 18 to the support stake 12. Also, such assembly ofthe preferred method of construction is readily recyclable. Again, thepreferred embodiment is not intended to be limiting in that the supportstakes 12 can be made of wood, metal, plastic, or wood composite and ofany convenient cross-section including the square cross-sectionillustrated in FIGS. 1-4.

It is foreseen that for some applications, the support stake 12 may bemade from a highly glass-filled polypropylene with a silt fabric screen18 and/or reinforcement member 22 made of polyolefin, polyester, nylon,or other woven or non-woven materials.

The silt fence assembly 10 is generally manufactured in rolls ofspecified lengths. This is accomplished by transversely attaching afirst support stake 12 to the silt fabric screen 18 and thereafterrotating the support stake 12 to wind the silt fabric screen 18 arounditself on the support stake 12. At preselected intervals, a secondsupport stake 12 is adhesively attached to the silt fabric screen 18 andthe winding continues until a complete roll of preselected length isformed. The roll can be made of any size; generally 100 foot rolls aretypical.

If a reinforcement member 22 is required, the same technique is usedexcept both the reinforcement member 22 and the silt fabric screen 18are adhesively attached to the first support stake 12 and wound togetheron the first support stake 12 until subsequent support stakes 12 areadhesively attached at selected intervals during the winding process.

The silt fence assembly 10 is installed in the field or at theconstruction site by unrolling the roll of preassembled support stakes12 and silt fabric screen 18 transverse to the anticipated direction ofwater flow. The beginning support stake 12 is then placed upright andthe pointed end 16 of the support stake 12 is anchored into the grounduntil the bottom edge of the silt fabric screen 18 comes into contactwith the ground. Subsequent support stakes 12 are then mounted into theground also across the direction of anticipated water flow, at adistance from the beginning support stake 12 that is sufficient to holdthe silt fabric screen 18 taut between the support stakes 12. Thesupplied roll is unwound as additional support stakes 12 are mounted inplace. After installation, the silt fabric screen 18 with or without thereinforcement member 22 will allow the passage of water but encouragethe deposition of sediment being carried by the water such that thesediment builds up on the upstream side of the silt fabric screen 18,resulting in the bottom edge of the silt fabric screen 18 ultimatelytending to bury itself. For some applications, a small shallow troughcan be made in the soil immediately underneath the silt fabric screen 18as it is spanned between support stakes 12. After the shallow depressionor trough is in place, the support stakes 12 are pounded to a slightlydeeper position so that the silt fabric screen 18 is in contact with thebottom surface of the depressed ground so that the bottom edge of thesilt fabric screen 18 is slightly below the ground level of the run-offwater. Such arrangement will greatly assist in the quick sedimentbuildup on the upstream side to ultimately bury the bottom edge of thesilt fabric screen 18 in the ground.

1. A silt fence for preventing soil erosion at construction sites, saidsilt fence comprising: a plurality of spaced apart stake members, eachof said plurality of stake members having a longitudinal bodyterminating at one end into a pointed end so as to enable anchoring ofeach of said plurality of stake members into the ground at saidconstruction site; a flexible fabric intimately disposed contiguous eachof said plurality of stake members and spanning the distance betweensaid plurality of stake members; and means for adhesively bonding saidflexible fabric to one of said plurality of stake members atpredetermined intervals, said means for adhesively bonding said flexiblefabric to one of said plurality of stake members comprising an adhesivethat is wettable with each of said plurality of stake members such thata molecular bond is formed, whereby when said silt fence is mounted in avertical position, across the anticipated direction of water flow, saidflexible fabric will allow the passage of water but encourage thedeposition of any sediment being carried by said water such that saidsediment builds up on the upstream side of said flexible fabricresulting in said flexible fabric ultimately tending to bury itself. 2.A silt fence for preventing soil erosion at construction sites, saidsilt fence comprising: at least two spaced apart stake members, each ofsaid at least two spaced apart stake members having a longitudinal bodyterminating at one end into a pointed end so as to enable anchoring saidat least two spaced apart stake members into the ground at saidconstruction site; a flexible fabric intimately disposed contiguous eachof said at least two spaced apart stake members and spanning thedistance between said at least two spaced apart stake members; and meansfor adhesively bonding said flexible fabric to said at least two spacedapart stake members, said means for adhesively bonding said flexiblefabric to said at least two spaced apart stake members comprising anadhesive that is wettable with said at least two spaced apart stakemembers such that a molecular bond is formed, whereby when said siltfence is mounted in a vertical position, across the anticipateddirection of water flow, said flexible fabric will allow the passage ofwater but encourage the deposition of any sediment being carried by saidwater such that said sediment builds up on the upstream side of saidflexible fabric resulting in said flexible fabric ultimately tending tobury itself.
 3. A method of making a silt fence, said method comprisingthe steps of: provide a roll of permeable silt fabric; provide aplurality of longitudinal stakes, each of said plurality of stakeshaving one end terminating in a pointed end; permanently attach one endof said roll of permeable silt fabric to one of said plurality of stakesusing an adhesive fastening means, said adhesive fastening meanscomprising an adhesive that is wettable with said outer surface of eachof said plurality of longitudinal stakes; rotate said one of saidplurality of stakes on its longitudinal axis and wind said roll ofpermeable silt fabric around said one of said plurality of stakes; at apreselected interval provide another of said plurality of stakes andpermanently attach said roll of permeable silt fabric to said another ofsaid plurality of stakes using said non-permeable fastening means;continue to rotate said one of said plurality of stakes on itslongitudinal axis and wind said roll of permeable silt fabric aroundsaid one and said another of said plurality of stakes and repeat saidpermanent attachment of said plurality of stakes until a roll is formed.4. The silt fence as claimed in claim 1 wherein said flexible fabric isa woven fabric.
 5. The silt fence as claimed in claim 1 wherein saidflexible fabric is a perforated sheet.
 6. The silt fence as claimed inclaim 1 wherein said flexible fabric is manufactured from plasticselected from olefin polymers, nylon, fiberglass, vinyl resins, orpolyesters.
 7. The silt fence as claimed in claim 6 wherein said olefinpolymers are selected from polypropylene and polyethylene.
 8. The siltfence as claimed in claim 1 wherein said adhesive is a fast cureadhesive.
 9. The silt fence as claimed in claim 8 wherein said fast cureadhesive is a hot melt adhesive.
 10. The silt fence as claimed in claim6 wherein said adhesive is a fast cure hot melt adhesive, with a surfacetension lower than 40 dynes/cm.
 11. The silt fence as claimed in claim 1further comprising a reinforcement member interposed said flexiblefabric and each of said plurality of stake members such that saidflexible fabric member and said reinforcement member are simultaneouslyattached to each of said plurality of stake members.
 12. The silt fenceas claimed in claim 11 wherein said flexible fabric, said reinforcementmember and each of said plurality of stake members are a thermoplasticmaterial selected from the group of olefin polymers, nylon, fiberglassor vinyl resins.
 13. The silt fence as claimed in claim 2 wherein saidflexible fabric is a woven fabric.
 14. The silt fence as claimed inclaim 2 wherein said flexible fabric is a perforated sheet.
 15. The siltfence as claimed in claim 2 wherein said flexible fabric is manufacturedfrom plastic selected from olefin polymers, nylon, fiberglass, vinylresins or polyester.
 16. The silt fence as claimed in claim 2 whereinsaid adhesive is a fast cure adhesive, with a surface tension of lowerthan 40 dynes/cm.
 17. The silt fence as claimed in claim 16 wherein saidfast cure adhesive is a hot melt adhesive.
 18. The silt fence as claimedin claim 15 wherein said adhesive is a hot melt adhesive.
 19. The siltfence as claimed in the claim 2 further comprising a reinforcementmember interposed said flexible fabric and each of said at least twospaced apart stake members such that said flexible fabric and saidreinforcement member are simultaneously attached to each of said atleast two spaced apart stake members.
 20. The silt fence as claimed inclaim 19 wherein said flexible fabric, said reinforcement member, andeach of said at least two spaced apart stake members are a thermoplasticmaterial selected from the group of olefin polymers, nylon, fiberglass,or vinyl resins.